Sulfur-containing polymers



United States Patent 3,317,488 SULFUR-CONTAINING POLYMERS Rudolf J. Eckert, Beuel (Rhine), Germany, and Lloyd C.

Fetterly, Oakland, Calif., assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Nov. 5, 1963, Ser. No. 321,430 4 Claims. (Cl. 260-79) This invention relates to novel and valuable sulfurcontaining polymers. More particularly, the invention relates to sulfur-containing polymers of ethylenically unsaturated compounds.

Specifically, the invention provides new and useful sulfur-containing polymers prepared by the process which comprises reacting an ethylenically unsaturated compound simultaneously with hydrogen sulfide and sulfur dioxide in the mole ratio of H S:SO of about 2: 1. The invention further relates to the process for preparing said polymers.

It is known that sulfur can be made to react with paraffins or olefins at elevated temperatures. However, in such instances the elemental sulfur (S is not the reacting agent under such conditions, i.e., the reacting sulfur is produced from S by heating at such high temperatures. It is also known that rubber has been vulcanized by alternating treatment of the unsaturated polymer with S0 and H S. It is further known that certain trialkyl-substituted ethylenes when alternatively treated with S0 and H 8 give organic tetrasulfides in extremely low yields (2-4%). These two processes are limited to rubber polymers and t-olefins and suffer from many disadvantages such as low yield, liquid phase reaction only, and no control of sulfur incorporated therein. As also noted above, the reaction is alternating and non-continuous with no control of relative amounts of S0 and H 8 since S0 is injected first in large excess.

It has now been unexpectedly discovered that sulfurcontaininig polymers of ethylenically unsaturated compounds may be prepared in either the liquid or vapor phase and wherein the amount of sulfur incorporated into the polymer is controlled by a process which comprises continuously and simultaneously reacting H 8 and S0 in a mole ratio of about 2:1 with an ethylenically unsaturated compound, preferably an unsaturated hydrocarbon.

It is therefore the primary object of the present invention to provide novel sulfur-containing polymers of unsaturated compounds in high yield. It is another object to provide a continuous process for preparing sulfur-containing polymers. These and other objects will become apparent from the following disclosure and discussion.

These and other objects are accomplished by the process of the present invention which comprises reacting an unsaturated compound simultaneously and continuously with H 8 and S0 in a mole ratio of from 1:1 to 3:1.

The sulfur-containing polymers of the present invention are useful for a wide range of purposes. They are particularly useful as additives where sulfur is desirable, such as, for example, to vulcanize rubbers and in insecticides. They are also useful as starting materials for reduction to dimercaptans and the like. In particular, the styrene-sulfur copolymer gives a clear, nearly odorless solution in solvents such as benzene and produce strong films with excellent adhesion to iron. Other polymers such as those from butadiene and isoprene remain plastic after standing for several months, yet contain as much as 75% or more sulfur. Normally, heretofore known products containing this amount of sulfur tended to crystallize in just a few weeks. Therefore, the present plastic polymers have numerous uses, especially in the field of low cost coatings and road paints. Further, the hydrogenasoluble enough in most tion of the allyl alcohol-sulfur copolymer yields the 1,2- dimercaptoglycerin analog, which is difficult to prepare by alternate means.

Thus, the process of the present invention offers several advantages over heretofore limited related processes in that the present process is continuous, control of the sulfur incorporated in the polymer is possible, and the process may be performed in either the vapor or-liquid phase. The instant process differs in at least one other material respect, i.e., the present process uses a ratio of H s to S0 of approximately 2: 1, whereas the prior processes use an excess of S0 injected into the process prior to the introduction of H 8 with subsequent alternating introduction of S0 The sulfur-containing polymers of the present invention are prepared by adding H 8 and S0 simultaneously in a mole ratio of about 2.: 1, respectively, to the ethylenically unsaturated compounds or to a solution thereof in an inert solvent under vigorous stirring and, generally, in the presence of a suitable catalyst. H 5 and S0 are common solvents to provide always a useful concentration of the two gases in the liquid phase. In general, the mole ratio of H 8 to S0 will range from about 1:1 to 3:1, although ratios outside this range may be employed. A mole ratio of 1.7:1 to 2.311 is preferred with a mole ratio of about 2:1 being especially prefered for most unsaturated monomers.

The unsaturated monomers which are suitable for the preparation of the sulfur copolymers of the present invention include the aliphatic acyclic olefins, particularly those having at least six carbon atoms such as hexene, heptene, octene, nonene, dodecene, cetene and the like, and more particularly the aliphatic conjugated diolefins such as butadiene, isoprene, piperylene, dimethyl butadiene, ethyl butadiene, and the like; cycloalkenes, such as cyclopentene, cyclohexene, cyclopentadiene, cycloheptene, cycloheptadiene, cyclooctene, cyclohexadiene, and the like; aryl olefins such as styrene, ring-substituted styrene such as chlorostyrene, 'bromostyrene, methylstyrene, rn-divinyl benzene and the like, and a-methyl styrene; vinyl compounds such as acrylonitrile, acrylic acid, methacrylonitrile, vinyl acetate, methyl methacrylate, ethyl acrylate, and vinyl chloride; allyl compounds such as allyl alcohol, allyl chloride, allyl acetate, cinnamyl bromide, cinnamyl acetate and cinnamyl alcohol; and unsaturated alkynearyl compounds such as phenyl acetylene and diphenylacetylene. Thus, suitable unsaturated monomers include those compounds containing a CHFC terminal group, i.e., a vinylidene group.

Suitable solvents for the monomers which may be employed as desired include, among others, aliphatic hydrocarbons such as pentane, hexane, heptane, octane, nonane, and the like; aromatic hydrocarbons such as benzene, toluene, xylene and the like, ethers such as diisopropyl ether, divinyl ether, diallyl ether and tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl butyl ketone and the like; and H S-SO solutions. Preferred sol-vents are benzene, pentane and tetrahydrofuran.

Although catalysts are not required to prepare the polymers of the present invention, a catalyst is generally employed. Liquid or vaporous water, even in trace quantities, is a very suitable catalyst. Other catalysts include, among others, pyridine, dimethylformamide, carbon disulfide, and other polar compounds such as alcohols, glycols and the like.

'The polymerization process may be performed at subdepending generally upon the monomers employed and whether a liquid or vapor phase polymerization is desired. Atmospheric or slightly superatmospheric pressures are preferred.

The process may be performed throughout a relatively wide temperature range, and generally a temperature range wherein the H 8 and S react and combine to form sulfur is employed. Such a temperature range'is sample was dried over P 0 and paraffin in vacuo at room temperature. The polymer had a softening point of 90100 C. and decomposed at 170 C. The analysis of the polymer was: C, 27%; H, 4.4%; S, 57.5%.

normally from about 90 C. to about 50 C. with the 5 Example H preferred range being from about C. to about C. It was found that this preferred range could be e Procedure of Example I Was essentially repeated ff ti l hi d by cooling the reaction i i wherein a number of other unsaturated monomers were Watch substituted for the allyl alcohol. The data and results T process f r preparing the new and valuable 1f 10 are generally tabulated in Table I. In all instances water containing polymers and their properties are illustrated Was used as the ys the feaellon time Was by the following examples. The reactants, their propor- Utes and the mole ratio of z z Was appfexlmately tions and other specific ingredients of the recipes are pre- 2: between about 1-711 and TABLE I Monomer Yields, 5. Polymer Analysis Unsaturated Amount, Solvent Reaction Polymer, Remarks Monomer ml. Phase mol. wt.

S Polymer C H S Cycloliexene 250 None Liquid 11 2.0 87.1 Styrene 100 200 m1. do 0 110 3,800 45.1 3.8 49.9 Product soluble in benzene, odorless THF and colorless; very little free sulfur; Eesin soft poitnggo8oloo (3.; resin ecomposesa a-l\1ethylstyreue. 100 20% do 60 3,000 48.4 4.5 45.7 Resin Softenst g0806100 C. and de- 4 composesa Divinylbenzene 150 lfig lillll. do vgrtyt1 51.9 4.8 41.0 Re sin gelled, ipslgkube in solvents,

1 e. ecomposesa Ethyl acrylate 150 15 01 d0 Little... 46 3,000 35.1 4.2 46.3 Benztenel-lsolublq odorless, transparen ye OW I'eSln. Butadiene 3:21! None Vapor S0n1e 13.5 2.4 72.5 Resin softening point: (SS-70 C.;decomposes}; wig-125E504 insoluble in mos mer SO ven Do 3;2;1 250 mil. Val.por-d None... 60 20.2 4.1 62.0 Viscous Zoroavn, oil; sets to rubber TH i ui upon s an ing. Do 1;4;2 250 ml. .f do.. Some 7.1 1.1 87.5 Yellow resin turns brown on stand- 10 0 mg. Isoprene 100 200 31 1 Liquid None. 40 32.1 4.3 66.7 Orange viscous oil which will cure 'IHF. rulbger rcemfints; sets to rubber SO] in 1V0 ays. Cinnamyl alcohol 100 150T do 135 350 64.3 6.0 20.2 Yellow, viscous oil product.

1 Molar ratio of butadieue: H;S=SO,. 2 VP osmometer, diehlorornethane. s Ebulliscopically in benzene. 4 VP osmoineter, methyl ethyl ketone.

sented as being typical and various modifications can be Example III mi 2 g g g?s is g igg g gzggfi g 3 1a; This example illustrates the effectiveness of an isopreueig m 6 p1 r s p sulfur copolymer as a vulcanizing agent.

' Twenty ml. of a 15.3 solution of a block polymer ig s ll gizygg z ig fggggf gi l g ifsf s z gfig 45 styrene-butadiene (1010010M) in cyclohexene were mixed with 0.9 gram of the isoprene-sulfur copolymer ml., three-necked flask fitted with a high-speed stirrmg means, two gas inlet tubes and one gas outlet tube was pr-ep'fired as m Examp 16 vulqamzatlon Pccurred utilizad as the reactor The rate of g addition was de within one-half hour at room temperature. The isoprenetermined by two flow meters During the reaction the fi g t wasdone day old when used for thls test an a s tu e.

reaction flask was cooled with an ice-water mlxture. The In an g 25 5 g z isoprene sulfur usual method was em lo ed to isolate the reaction roducts ie the reactio i products were filtered and the 3 er was i 20 of cartes cliar Gnp u er cement. u canization occurre wit in two filrrzgte evaporated to obtain the soluble reaction polyhours at room temperature Example I Example IV Into the above-described reactor were placed 300 ml. The Procedure of Example I Was Substantially repeated of allyl alcohol. Then under ice-water cooling and Vigorwherein the unsaturated monomer was n-hexadecene-l. ous stirring, 2 molar parts of H 3 d 1 molar part of Anearly colorless waxy product was formed, which could S0 were introduced simultaneously for one hour. The be recrystallized from ethanol and melted at yellow precipitate (sulful) was separated by filtration A molecular Weight of 482 Was determined y mass p and dried (25 gr.). The filtrate was evaporated in vacuo PY at room temperature and yielded 27 grams of a yellow Example V res1n. The resin became rubbery after a few days. The procedure of Example I is substantially repeated If the introduction of the hydrogen sulfide and sulfur wherein the unsaturated com d i henyl acetylene dioxide is continued for a longer time, the allyl alcohol- A yellow polymer is obtaineg p sulfur polymer will also separate together with the free sulfur. In such a case the mixture was dissolved in Example V1 g l yi fi 115mg 8 SOXhlet unlt. Then f This example demonstrates the approximate structure c estiprvept, t e free sulfur was separated by fractional of the styrene-sulfur copolymer.

Z S 2 21 cunt Wa fi d b h The polymer products prepared from styrene and aluminum Oxide (A/8113 6 Y i m l p y H S/SO are oil-soluble and have a pleasant odor. The THF as 1 Af l actlvlty I) eepelymer 1S med to be an alternating linear polymer 5 ter evaporanon of the Solvent the ha g Q or more sulfur groups per monomer unit wherein 11:2, 3, 4, etc., with 3 being usual, and x is about 15-25.

A solution of 15 grams of a styrene-sulfur copolymer having an assumed structure of and a molecular weight of 3800:200 (viscosimetric determination in dichlor-omethane) in 100 ml. of dry THF was added dropwise to a suspension of 6 grams lithium aluminum hydride in 250 ml. of dry THF under a nitrogen atmosphere. After the addition was complete, the reaction mixture was heated to 70 C. for five minutes. The solution was then cooled with ice and enough isopropanol was added to destroy the excess reducing agent. The reaction products were then hydrolyzed with 150 ml. of N HCl, causing the formation of two layers. The acidic mixture was extracted three times with ether. The ether extracts were dried over magnesium sulfate and evaporated under reduced pressure at room temperature. The resulting pale yellow liquid (10 g.) had the characteristic mercaptan odor and likely following structure:

CHzSH CH-SH 2.1 grams of the crude mercaptan were added dropwise to a solution of 5 grams AgNO in 50 ml. of water.

A yellow precipitate yield) was formed immediately and was filtered after one hour, washed with copious amounts of water, dried over P 0 in vacuo at room temperature, and analyzed.

Calculated (for C H S Ag277.2): C, 34.7; H, 3.2; S, 23.1; Ag, 38.9. Found: C, 36.3 H, 3.2; S, 19.1; Ag, 35.6.

The NMR spectrum of the liquid is in complete accordance with the expected mercaptan structure: 5 aromatic hydrogen, 2 mercapto hydrogen and 3 aliphatic hydrogen atoms were found.

We claim as our invention:

1. A process for preparing plastic sulfur-containing polymers which comprises reacting at a temperature of from l0 C. to 15 C. an ethylenically unsaturated compound selected from the group consisting of (a) aliphatic acyclic olefins containing at least 6 carbon atoms, (b) aliphatic conjugated diolefins containing from 4 to 6 carbon atoms, (c) cycloalkenes, (d) aryl olefins and (e) ethyl acrylate with a mixture of hydrogen sulfide and sulfur dioxide in the mole ratio of H S:SO of from 1:1 to 3:1.

2. A process as in claim 1 wherein the aliphatic conjugated diene is butadiene.

3. A process as in claim 1 wherein the aryl olefin is styrene.

4. A process as in claim 1 wherein the conjugated diene is isoprene.

References Cited by the Examiner UNITED STATES PATENTS 3,231,546 Bertozzi et al. 260-79 OTHER REFERENCES 52 Chemical Abstracts, page 2482b (1958). 57 Chemical Abstracts, page 8166b (1962).

DONALD E. CZAJA, Primary Examiner.

LEON J. BERCOVITZ, M. I. MARQUIS,

Assistant Examiners.

Hendry et a1. 26079. 

1. A PROCESS FOR PREPARING PLASTIC SULFUR-CONTAINING POLYMERS WHICH COMPRISES REACTING AT A TEMPERATURE OF FROM -10*C. TO 15*C. AN ETHYLENICALLY UNSATURATED COMPOUND SELECTED FROM THE GROUP CONSISTING OF (A) ALIPHATIC ACYCLIC OLEFINS CONTAINING AT LEAST 6 CARBON ATOMS, (B) ALIPAHTIC CONJUGATED DIOLEFINS CONTAINING FROM 4 TO 6 CARBON ATOMS, (C) CYCLOALKENES, (D) ARYL OLEFINS AND (E) ACRYLATE WITH A MIXTURE OF HYDROGEN SULFIDE AND SULFUR DIOXIDE IN THE MOLE RATIO OF H2S:SO2 OF FROM 1:1 TO 3:1. 